Performance issues after scaling up Azure Database for PostgreSQL - Flexible Server

@Tigran Sardaryan

Thank you for the question and for using Microsoft Q&A platform.
As per my understanding you are facing with Performance issues after scaling up Azure Database for PostgreSQL - Flexible Server with no change in server parameters.
Here are some possible reasons for the performance decrease after upgrading to the D16ds_v5 instance:

Resource Allocation and Configuration

• CPU and Memory Utilization: Verify that the additional vCores and RAM are being effectively utilized. Applications or queries might need adjustments to take full advantage of these increased resources.
• Connection Pooling: Check if your connection pooling settings are optimized. Excessive short-lived connections can lead to high CPU usage.

I/O Performance

• Disk I/O: With the change in storage size, I/O performance characteristics may have shifted. Ensure that I/O operations aren't becoming a bottleneck.
• Storage Configuration: Confirm that the storage configuration (such as IOPS and throughput) is suitable for your workload requirements.

Query Performance

• Query Plans: The query execution plans might have been altered due to the new hardware configuration. Review and optimize query plans as needed.
• Indexing: Ensure that indexes remain effective with the new setup. Hardware changes can sometimes affect indexing performance.

Auto vacuum and Maintenance

• Auto vacuum Settings: Verify that autovacuum settings are still appropriate. Inefficient autovacuum settings can cause performance degradation.
• Maintenance Tasks: Make sure that regular maintenance tasks, like vacuuming and analyzing, are running as expected.

Additionally, you can utilize the Troubleshooting Guides in the Azure portal to diagnose specific issues like high CPU usage, memory constraints, or I/O performance bottlenecks. These guides provide tailored charts, guidelines, and recommendations to address your specific performance challenges.

For more information, please refer to the below links:
https://techcommunity.microsoft.com/blog/adforpostgresql/empower-your-troubleshooting-with-azure-database-for-postgresql---flexible-serve/3794263
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-high-cpu-utilization?tabs=postgres-13
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-high-io-utilization
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-autovacuum-tuning
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-identify-slow-queries
https://learn.microsoft.com/en-us/azure/postgresql/flexible-server/how-to-optimize-query-stats-collection

Hope this helps. Please let us know if you have any further questions.